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Annotation of GNUtools/emacs/src/unexenix.c, revision 1.1

1.1     ! root        1: /* Unexec for Xenix.
        !             2:    Copyright (C) 1988 Free Software Foundation, Inc.
        !             3: 
        !             4:    Note that the GNU project considers support for Xenix operation
        !             5:    a peripheral activity which should not be allowed to divert effort
        !             6:    from development of the GNU system.  Changes in this code will be
        !             7:    installed when Xenix users send them in, but aside from that
        !             8:    we don't plan to think about it, or about whether other Emacs
        !             9:    maintenance might break it.
        !            10: 
        !            11:     This program is free software; you can redistribute it and/or modify
        !            12:     it under the terms of the GNU General Public License as published by
        !            13:     the Free Software Foundation; either version 1, or (at your option)
        !            14:     any later version.
        !            15: 
        !            16:     This program is distributed in the hope that it will be useful,
        !            17:     but WITHOUT ANY WARRANTY; without even the implied warranty of
        !            18:     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
        !            19:     GNU General Public License for more details.
        !            20: 
        !            21:     You should have received a copy of the GNU General Public License
        !            22:     along with this program; if not, write to the Free Software
        !            23:     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
        !            24: 
        !            25: In other words, you are welcome to use, share and improve this program.
        !            26: You are forbidden to forbid anyone else to use, share and improve
        !            27: what you give them.   Help stamp out software-hoarding!  */
        !            28: 
        !            29: 
        !            30: /*
        !            31:   On 80386 Xenix, segmentation screws prevent us from modifying the text
        !            32:   segment at all.  We basically just plug a new value for "data segment
        !            33:   size" into the countless headers and copy the other records straight
        !            34:   through.  The data segment is ORG'ed at the xs_rbase value of the data
        !            35:   segment's xseg record (always @ 0x1880000, thanks to the "sophisticated
        !            36:   memory management hardware" of the chip) and extends to sbrk(0), exactly.
        !            37:   This code is afraid to malloc (should it be?), and alloca has to be the
        !            38:   wimpy, malloc-based version; consequently, data is usually copied in
        !            39:   smallish chunks.
        !            40: 
        !            41:   [email protected]
        !            42: */
        !            43: 
        !            44: #include "config.h"
        !            45: #include <sys/types.h>
        !            46: #include <fcntl.h>
        !            47: #include <sys/file.h>
        !            48: #include <sys/stat.h>
        !            49: #include <stdio.h>
        !            50: #include <varargs.h>
        !            51: #include <a.out.h>
        !            52: 
        !            53: static void fatal_unexec ();
        !            54: 
        !            55: #define READ(_fd, _buffer, _size, _error_message, _error_arg) \
        !            56:        errno = EEOF; \
        !            57:        if (read(_fd, _buffer, _size) != _size) \
        !            58:          fatal_unexec(_error_message, _error_arg);
        !            59: 
        !            60: #define WRITE(_fd, _buffer, _size, _error_message, _error_arg) \
        !            61:        if (write(_fd, _buffer, _size) != _size) \
        !            62:          fatal_unexec(_error_message, _error_arg);
        !            63: 
        !            64: #define SEEK(_fd, _position, _error_message, _error_arg) \
        !            65:        errno = EEOF; \
        !            66:        if (lseek(_fd, _position, L_SET) != _position) \
        !            67:          fatal_unexec(_error_message, _error_arg);
        !            68: 
        !            69: extern int errno;
        !            70: extern int sys_nerr;
        !            71: extern char *sys_errlist[];
        !            72: #define EEOF -1
        !            73: 
        !            74: #ifndef L_SET
        !            75: #define L_SET 0
        !            76: #endif
        !            77: 
        !            78: /* Should check the magic number of the old executable;
        !            79:    not yet written.  */
        !            80: check_exec (x)
        !            81:      struct xexec *x;
        !            82: {
        !            83: }
        !            84: 
        !            85: 
        !            86: unexec (new_name, a_name, data_start, bss_start, entry_address)
        !            87:      char *new_name, *a_name;
        !            88:      unsigned data_start, bss_start, entry_address;
        !            89: {
        !            90:   char *sbrk (), *datalim = sbrk (0), *data_org;
        !            91:   long segpos, textseen, textpos, textlen, datapos, datadiff, datalen;
        !            92: 
        !            93:   struct xexec u_xexec,       /*  a.out header */
        !            94:               *u_xexecp = &u_xexec;
        !            95:   struct xext  u_xext,        /*  extended header */
        !            96:               *u_xextp  = &u_xext;
        !            97:   struct xseg  u_xseg,        /*  segment table entry */
        !            98:               *u_xsegp  = &u_xseg;
        !            99:   int i, nsegs, isdata = 0, infd, outfd;
        !           100: 
        !           101:   infd = open (a_name, O_RDONLY, 0);
        !           102:   if (infd < 0) fatal_unexec ("opening %s", a_name);
        !           103: 
        !           104:   outfd = creat (new_name, 0666);
        !           105:   if (outfd < 0) fatal_unexec ("creating %s", new_name);
        !           106: 
        !           107:   READ (infd, u_xexecp, sizeof (struct xexec),
        !           108:        "error reading %s", a_name);
        !           109:   check_exec (u_xexecp);
        !           110:   READ (infd, u_xextp, sizeof (struct xext),
        !           111:        "error reading %s", a_name);
        !           112:   segpos = u_xextp->xe_segpos;
        !           113:   nsegs = u_xextp->xe_segsize / sizeof (struct xseg);
        !           114:   SEEK (infd, segpos, "seek error on %s", a_name);
        !           115:   for (i = 0; i < nsegs; i ++)
        !           116:     {
        !           117:       READ (infd, u_xsegp, sizeof (struct xseg),
        !           118:            "error reading %s", a_name);
        !           119:       switch (u_xsegp->xs_type)
        !           120:        {
        !           121:        case XS_TTEXT:
        !           122:          {
        !           123:            if (i == 0)
        !           124:              {
        !           125:                textpos = u_xsegp->xs_filpos;
        !           126:                textlen = u_xsegp->xs_psize;
        !           127:                break;
        !           128:              }
        !           129:            fatal_unexec ("invalid text segment in %s", a_name);
        !           130:          }
        !           131:        case XS_TDATA:
        !           132:          {
        !           133:            if (i == 1)
        !           134:              {
        !           135:                datapos = u_xsegp->xs_filpos;
        !           136:                datalen = datalim - (data_org = (char *)(u_xsegp->xs_rbase));
        !           137:                datadiff = datalen - u_xsegp->xs_psize;
        !           138:                break;
        !           139:              }
        !           140:            fatal_unexec ("invalid data segment in %s", a_name);
        !           141:          }
        !           142:        default:
        !           143:          {
        !           144:            if (i > 1) break;
        !           145:            fatal_unexec ("invalid segment record in %s", a_name);
        !           146:          }
        !           147:        }
        !           148:     }
        !           149:   u_xexecp->x_data = datalen;
        !           150:   u_xexecp->x_bss = 0;
        !           151:   WRITE (outfd, u_xexecp, sizeof (struct xexec),
        !           152:         "error writing %s", new_name);
        !           153:   WRITE (outfd, u_xextp, sizeof (struct xext),
        !           154:         "error writing %s", new_name);
        !           155:   SEEK (infd, segpos, "seek error on %s", a_name);
        !           156:   SEEK (outfd, segpos, "seek error on %s", new_name);
        !           157: 
        !           158:   /* Copy the text segment record verbatim. */
        !           159: 
        !           160:   copyrec (infd, outfd, sizeof (struct xseg), a_name, new_name);
        !           161: 
        !           162:   /* Read, modify, write the data segment record. */
        !           163: 
        !           164:   READ (infd, u_xsegp, sizeof (struct xseg),
        !           165:        "error reading %s", a_name);
        !           166:   u_xsegp->xs_psize = u_xsegp->xs_vsize = datalen;
        !           167:   u_xsegp->xs_attr &= (~XS_AITER & ~XS_ABSS);
        !           168:   WRITE (outfd, u_xsegp, sizeof (struct xseg),
        !           169:         "error writing %s", new_name);
        !           170: 
        !           171:   /* Now copy any additional segment records, adjusting their
        !           172:      file position field */
        !           173: 
        !           174:   for (i = 2; i < nsegs; i++)
        !           175:     {
        !           176:       READ (infd, u_xsegp, sizeof (struct xseg),
        !           177:            "error reading %s", a_name);
        !           178:       u_xsegp->xs_filpos += datadiff;
        !           179:       WRITE (outfd, u_xsegp, sizeof (struct xseg),
        !           180:             "error writing %s", new_name);
        !           181:     }
        !           182: 
        !           183:   SEEK (infd, textpos, "seek error on %s", a_name);
        !           184:   SEEK (outfd, textpos, "seek error on %s", new_name);
        !           185:   copyrec (infd, outfd, textlen, a_name, new_name);
        !           186: 
        !           187:   SEEK (outfd, datapos, "seek error on %s", new_name);
        !           188:   WRITE (outfd, data_org, datalen,
        !           189:         "write error on %s", new_name);
        !           190: 
        !           191:   for (i = 2, segpos += (2 * sizeof (struct xseg)); 
        !           192:        i < nsegs;
        !           193:        i++, segpos += sizeof (struct xseg))
        !           194:     {
        !           195:       SEEK (infd, segpos, "seek error on %s", a_name);
        !           196:       READ (infd, u_xsegp, sizeof (struct xseg),
        !           197:            "read error on %s", a_name);
        !           198:       SEEK (infd, u_xsegp->xs_filpos, "seek error on %s", a_name);
        !           199:       /* We should be at eof in the output file here, but we must seek
        !           200:          because the xs_filpos and xs_psize fields in symbol table
        !           201:         segments are inconsistent. */
        !           202:       SEEK (outfd, u_xsegp->xs_filpos + datadiff, "seek error on %s", new_name);
        !           203:       copyrec (infd, outfd, u_xsegp->xs_psize, a_name, new_name);
        !           204:     }
        !           205:   close (infd);
        !           206:   close (outfd);
        !           207:   mark_x (new_name);
        !           208:   return 0;
        !           209: }
        !           210: 
        !           211: copyrec (infd, outfd, len, in_name, out_name)
        !           212:      int infd, outfd, len;
        !           213:      char *in_name, *out_name;
        !           214: {
        !           215:   char buf[BUFSIZ];
        !           216:   int chunk;
        !           217: 
        !           218:   while (len)
        !           219:     {
        !           220:       chunk = BUFSIZ;
        !           221:       if (chunk > len)
        !           222:        chunk = len;
        !           223:       READ (infd, buf, chunk, "error reading %s", in_name);
        !           224:       WRITE (outfd, buf, chunk, "error writing %s", out_name);
        !           225:       len -= chunk;
        !           226:     }
        !           227: }
        !           228: 
        !           229: /*
        !           230:  * mark_x
        !           231:  *
        !           232:  * After succesfully building the new a.out, mark it executable
        !           233:  */
        !           234: static
        !           235: mark_x (name)
        !           236:      char *name;
        !           237: {
        !           238:   struct stat sbuf;
        !           239:   int um = umask (777);
        !           240:   umask (um);
        !           241:   if (stat (name, &sbuf) < 0)
        !           242:     fatal_unexec ("getting protection on %s", name);
        !           243:   sbuf.st_mode |= 0111 & ~um;
        !           244:   if (chmod (name, sbuf.st_mode) < 0)
        !           245:     fatal_unexec ("setting protection on %s", name);
        !           246: }
        !           247: 
        !           248: static void
        !           249: fatal_unexec (s, va_alist)
        !           250:     va_dcl
        !           251: {
        !           252:   va_list ap;
        !           253:   if (errno == EEOF)
        !           254:     fputs ("unexec: unexpected end of file, ", stderr);
        !           255:   else if (errno < sys_nerr)
        !           256:     fprintf (stderr, "unexec: %s, ", sys_errlist[errno]);
        !           257:   else
        !           258:     fprintf (stderr, "unexec: error code %d, ", errno);
        !           259:   va_start (ap);
        !           260:   _doprnt (s, ap, stderr);
        !           261:   fputs (".\n", stderr);
        !           262:   exit (1);
        !           263: }

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